Bill Bratton, the former police commissioner of Boston and New York City as well as former chief of police in Los Angeles, discusses the Boston Marathon bombings, saying the FBI "will be going in many directions" as they continue to investigate.

By Ian Johnston, Staff Writer, NBC News

LONDON -- Former Boston Police Commissioner Bill Bratton said Tuesday that those responsible for the bombing of the city’s marathon should be put to death.

Bratton said he had “every confidence” that the authorities would “get to the bottom of this and bring those responsible to justice.”

Massachusetts abolished capital punishment in 1984, but Bratton said the federal authorities could take over the prosecution of terrorist acts like this and a federal court could pass the death sentence.

“I think this act would be an appropriate use of the death penalty as a penalty for the crime,” he said.

Bratton, who was born and raised in the city and policed its marathon for many years, said he was having dinner in the British capital when he started getting emails about the bomb blasts.

He spent the next few hours trying to find out what happened and whether people close to him had been hurt or killed.

“I’ve friends and relatives that would be at that event, some running in it, some observing,” Bratton said, adding that former police colleagues would also have been there providing security.

'No shortage of haters'Bratton, who was also previously chief of the Los Angeles Police Department and New York's police commissioner, said there were a number of potential suspects, including al Qaeda.

“You line up the usual suspects and they’d certainly be at the front of the line, but unfortunately there’s no shortage of haters, people who don’t like the government … neo-Nazi types … any number of people are capable of wanting to participate and pull of this type of event,” he said.

But Bratton cautioned against anyone jumping to conclusions or indulging in “idle speculation” about who had carried out the attack and said people should allow law enforcement officers to deal with the investigation.

He said the authorities had been successful in preventing many terrorist attacks in the U.S., including "at least a dozen" in New York City, where he now lives.